Image editing software applications have been developed to adjust, modify, and otherwise manipulate digital images. Examples of image editing software applications include Adobe® Photoshop® (Adobe Systems Incorporated, San Jose, Calif.), Corel® Paint Shop Pro® (Corel Corporation, Ottawa, Canada), and Audodesk® SketchBook® (Autodesk, Inc., San Rafael, Calif.). Applications such as these generally allow a user to make global manipulations to an entire image as well as localized manipulations that affect only a selected portion of an image. The ability to make localized manipulations can be useful if a user wishes to, for example, adjust the brightness of a person's face, change the color hue of a flower, or extract foreground objects from a background scene. Regardless of the particular type of image processing which is to be performed, making localized manipulations generally comprises a two-step process of first selecting a portion of the image that is to be manipulated and then applying the desired manipulation to that selection. The initial process of selecting the portion of the image that is to be manipulated is sometimes referred to as “segmentation” of the image.